Refining raw lube oil stock with a mild hydrogen treatment followed by sulfuric acid



REFINING RAW LUBE OIL STOCK WITH A .MILD

HYDROGEN TREATMENT'FOLLOWED BY SUL- FURICACID William B. Watson, ParkForest, IlL, assignor to Sinclair Refining Company, New York, N.Y., acorporation of Maine- No Drawing. Filed Feb. 6, 1958, Ser. No. 713,539

2 Claims. (Cl. 208-264) sultant sludge to 'producean acid oil layer,removing the sludge, neutralizing the sulfonic acids and unreactedsulfuric acid present in the'acid oil layer with a base material such assodium hydroxide, potassium hydroxide, ammonium hydroxide, or sodiumcarbonate in Water solution, e.g., 20 percent solution, and waterwashing to remove excess base and toyielda neutral oil. The amount ofacid required depends upon the strength of the acid employed, and theviscosity of the distillate being treated. Acid dosages can vary over awider range, but, in general, vary from about 5 pounds per barrel of 50SUS/ 100 F. (ASTM D 88) distillate to about 50 pounds per barrel of6,000 SUS/ 100 F. distillate. Sulfuric acid strength can vary, ingeneral, from about 85 weight percent to Weight percent oleum, but 93 to98 Weight percent sulfuric acid is most often employed.

There are numerous modifications for sulfuric acidtreating oils andremoving the sludge formed by the acid treatment. However, regardless ofthese modifications, this process has a major drawback in that asubstantial quantity of, for instance, a raw lube fraction is convertedto a sludge material of little or no value.

I have now found that, if the raw stock is hydrogenated prior to thesulfuric acid-treating step, higher yields of finished oil are obtainedand, in addition, lesser amounts of acid are required in theacid-treating step. By increasing the yield on acid-treating anddecreasing the amounts of acid required, the overall costs of my processare considerably less than those of a straight sulfuric acid-treatingprocess.

My process has been found to be particularly eiiective in thepreparation of lubricating oils from distillates'of naphthenic basecrudes, e.g., Gulf Coast and California crudes. Such crude oils, if theycontain wax, are, preferably, dewaxed prior to the hydrogenation stepand the acid-treating step, although the dewaxing can follow thehydrogenation operation. This dewaxing can be carried out, for example,by solvent dewaxing using methyl ethyl ketone and toluene as the solventto achieve oil of below F. pour point (ASTM D 97). The pour point afterdewaxing is determined by that required in the finished oil.

The hydrogenation step of my process involves employing a hydrogenationcatalyst. Various methods for manufacturing such catalysts have beendescribed in the art, such as in Byrns Patent 2,325,033, and suchcatalysts generally consist of from about 2 to 5 percent by weight ofcobalt oxide and 5 to 15 percent by weight of molybdic oxide, thebalance being alumina. Also useful are, for instance, nickel onporcelain, silica or alumina; molybdenum, tungsten, cobalt, nickeloxides and sulfides; and, platinum and palladium on alumina. A preferredcatalyst is cobalt molybdate supported'on :aluminapr'epared by themethod .of Keith .et al. described in copending application .Ser. .No.612,892, .filedSeptemb'er 28, 1956;

Further, inthe hydrogenation step of .my. process, a temperature of from550 to 75.0". R, .apressure of from 400 to 1500. p.s.i.g. anda weighthourly-spacevelocity (weightunits of .oilper weight unit of catalyst perhour) of .from 0.5 .to 5.0 .are used. The oil is hydrogenated while itisin admixture with from 700 to 5000 standard cubic feet of hydrogenper'barrel o f oil;v

'A'specific example which 'illustrates-lriyprocess and compares it withthe known process of acidtreating and then neutralizing .a charge stockwithout a .prior hydrogenation is as follows: a

Two portions of Gulf Coast reduced crude were vacuum distilled to yielddistillate portions having'the following characteristics:

Gravity, API(ASTM D287) I 19.9 Flash, F.'(ASTM D '92 440 Viscosity,SUS/l'0'0" F. (ASTM 'D'88)' 159.4 Viscosity,'SUS/2l0 F. (ASTM'D'88)'8l.12 Viscosity index (ASTM D 567) 9.9 Pour, (ASTM'D '97) f5-'-ColorfNPA (ASTM D155) '8- Specific dispersion 5,141.9 Aniline point, 1C.1(A-STM .D.-.6l 1:).

Reference: The Chemical Constituents of Petroleum, by A. N. Sachanen,page 109, published by. Reinhold Publishing Corporation in 1945. and'Elines of mercury were used in refractometer measurements and temperaturewas 20 C.

The first distillate portion was then hydrogenated With 1500 standardcubic feet of hydrogen per barrel 'of'dis; tillate at a temperature of700 F. and a pressure of 500 p.s.i.g. by passing it into contact with acobalt molybdate on alumina catalyst at a weight hourly space velocityof 3.0. The catalyst used analyzed, on an ignited basis, 2.45 weightpercent cobalt, 8.53 Weight percent molybdic oxide and the remainderalumina.

The weight yield of hydrogenated distillate after being lightly steamstripped was 99.9 percent, and the resulting product had the followingcharacteristics:

The steam-stripped, hydrogenated oil wassubjected to sulfuric acidtreatment. The strength of the acid employed was 98 Weight percent andthe acid dosage Was 16 pounds of acid per barrel of oil. The acid oilmixture was mixed for 45 minutes at a temperature of from to F. It wasthen allowed to settle for 16 hours and sludge was drawn olf. The acidoil mixture was then subjected to an air blow for 2 hours and againallowed is not essential to the process. acid treated, neutralized,contacted oil were as follows:

Gravity, API 21.3 Flash, F. 425 Viscosity, SUS/ 100 F. 1205 Viscosity,SUS/210 F. 74.47 Viscosity index 24.8 Pour, F. Color, NPA 2+ Specificdispersion 131.4 Aniline point, C. 91.4

The second portion of the vacuum distilled Gulf Coast reduced crude oilwas acid treated by the same procedure employed for the first portion,but without prior hydrogenation. In this instance, 32 pounds of 98weight percent sulfuric acid per barrel of distillate were required andthe yield of finished oil, i.e., after neutralization, was 86.0 percentby weight. Such finished oil had the follow- Thus, a comparison of theprocedures used on and the products derived from the two portions ofGulf Coast The characteristics of the 4 v reduced crude vacuumdistillate shows that, although the products are essentially equivalentin degree of refining in terms of viscosity indices, specificdispersions and aniline points, the product of my process ofhydrogenating before acid treating and neutralizing required one-half ofthe acid used in the known process of acid treating and neutralizing. Inaddition, the yields, when employing my process, were 5.4 percent higherthan that of when the old process was employed.

I claim:

1. In the refining of a raw petroleum lubricating oil, the stepsconsisting essentially of passing the lubricating oil and hydrogen intocontact with a hydrogenation catalyst at a temperature within the rangefrom 550 F. to 750 F. and at a pressure within the range 400 to 1500p.s.i.g. to provide a hydrogenated oil and then treating thehydrogenated oil with sulfuric acid to provide an acid oil, said rawlubricating oil being derived from a naphthenic base crude selected fromthe group consisting of Gulf Coast and California crudes.

2. The method of claim 1 wherein said catalyst is cobalt molybdatesupported on alumina.

References Cited in the file of this patent UNITED STATES PATENTS1,847,623 Ott Mar. 1, 1932 2,692,226 Smith Oct. 19, 1954 2,706,167Harper et a1. Apr. 12, 1955 2,779,711 Goretta Ian. 29, 1957 2,779,713Cole et al J an. 29, 1957

1. IN THE REFINING OFD A RAW PETROLEUM LUBRICATING OIL, THE STEPSCONSISTING ESSENTIALLY OF PASSING THE LUBRICATING OIL AND HYDROGEN INTOCONTACT WITH A HYDROGENATION CATALYST AT A TEMPERATURE WITHIN THE RANGEFROM 550* F. TO 750* F. AND AT A PRESSURE WITHIN THE RANGE 400 TO 1500P.S.I.G. TO PROVIDE A HYDROGENATED OIL AND THEN TREATING THEHYDROGENATED OIL WITH SULFURIC ACID TO PROVIDE AN ACID OIL, SAID RAWLUBRICATING OIL BEING DERIVED FROM A NAPHTHENIC BASE CRUDE SELECTED FROMTHE GROUP CONSISTING OF GULF COAST AND CALIFORNIA CRUDES.